Multiplex radiotelephony



'1. H. HAMMOND, In.

- MULTIPLEX RADIOTELEPHONY. APPLICATIONYHLED MAY 2-9, 1912. RENEWED MAR.15,1919.

1,372,426. Patented Mar.22, 1921.-

WITNESSE a MZE/VTOR V I A! izz' w" ORNEYS Mi i UNITED STATES PATENTOFFICE.

JOHN HAYS HAMMOND, J 3, OF GLOUCESTER, MASSACHUSETTS.

- MULTIPLEX nanio rnnnrnony.

'. Specification of Letters Patent -Pa tenf ed luau 22 19,21,

Application iiled I May 29, 1912, Serial No. 700,426. lienewed March I5,1919. Serial No. 282,960.

To ditwhom it may concern:

siding at Gloucester, in the-State of Messachusetts-have inventedcertain -new and useful Improvements in. Multiplex Radio ficat-ioii. y y

My invention relates to systems for transmitting and receiving two ormore telephoneconversations simultaneously by meansof electric waves;and relates more particularly to such systems where electric. ,waveshaving different lengthsai'e employed for this simultaneous ormultiplex, te- Hei'etofoi'etwo oscillation genera-tors have been used atthe transmitting station, each generating electric waves of a definitelength, but by my inventionit is possible to use only one generator forgenerating any required number of sets of clectric waves, the wavesin-each sethaving difierent-lengths from those in the other sets. v:This will be shown more fully by the following description,' referencebe ng had to the accompanyingdrawings;

Figure l shows-atransmitting stationon my system of multiplex radiotelephony I F 2 shows a corresponding receiving L station on'mysystem; ar y In 'Fig '1,' an oscillatory arc-O is suRpl iTd from a source ofdirect current shunted around Ozare two-oscillating cirij cuits O'LGandOL C containing the inductan'ce coilsL and--L ,and the condensers Cand C respectively, which are in resonancewith the antenna circuits A LT E and A T 515, respectively,- towhich they .are v respectively:coupled through the coils- L 40 and L p; ,It is'well known that anelectric arc of thetype shown comprises-two elec- 5: trodes, one of'whiclnthe cathode, is always negative, and emits electrons when in operation. J'The are 0 eonstitutes ajthermionic oscillator. i The antennais grounded 1 atg E, and Jasthecircuits 0L G and 0 I30 have differentosci llation' periods, the an tennal A--will radiate continuousunclam'ped In 2, B is-an antenna grounded at telephony. of which thefollowingis aspeci- E and having two circuits B Li C E and B L C E thesecircuits containing the inductancecoils, L and L, and the 3condensers,'C ,and (3*,"respectively, and being coupled to theclosedoscillation circuits L C and L 0? through the coils L and L,respectively. The. antenna circuit B L C and the oscillation -circuit L5(3* are in resonance with each other and with one of 'thewave-frequencies of the transmitting rectifier will deliver,unidirectional cur-' i rent corresponding to the current"variationscaused by the transmitter T, in Fig. 1,-to

the telephone receiver P where the sounds produced at will bereproduced. V In like" manner whenthe circuit L C is energized,

- the rectifier .R -w-i-ll deliver unidirectional current tothetelephone P which will thus Although in the particular embodiment'of'my invention here shown there are only two sets of circuits,- andonly two telephone conversations can be carried on vsirnultaneously. myinvention is not limited to two sets,

of circuits, but may employ three or more sets of circuits, so thatthree. or more telephone conversations can be carried onsimultane'ously. Instead. of "telephone appa 'ratus I canemploytelegraph apparatus at of two or' morextelegraph messages,- or- I canusebothvtelephoneandtelegraph apparatus at both transmittingand'ireceiving."

9 stations andtransini't and receive telephone conversationsand:telegraph messages Jsilmultaiieoiislyz And, "moreover; IFtlo not*confine myself to the particular a aratus or, circuits-here shown, butmay em )loyany otlierapparatu s tor arrangement 9 circzuits' suitableforimy 'purpose: a

I iclaim as my invention I q f 1. In wa sysftem oi multiplex radio tele'p hony," e plurality of oscillation circuits connected with a:single-arc, said oscillation circuits haviingdiiferent periodicities,secondary circuitcoupled to each of said oscilla- 1 1 o t on oircuitsandconnected to a s ngle antenna, a telephone transmitter in operativej'relation "to each of said secondary circuits,

and a receiving station comprising a plurality of circuits tuned to thedlflerent wave lengths-emittedby the transmitting station. 2. A systemof multiplex radio telephony having a transmitting station comprising asingle are connected with a source of en-- ergy, a plurality of circuitsin. parallel conreceiving station comprising a plurality of circuitstuned to the wave lengths of the transmitting station, and operativelycon- 6 nected with telephone receiving apparatus.

3. In a system of-electricwave transmission,'a plurality of oscillationcircuits connected with a sin 1e arc, said oscillation circuits havingdi erent periodicities secondary circuits coupled to each of saidoscillation circuits and connected to a single antenna, and a;receivingvstation co g; ing -P y of circuits tuned to they differentwave lengths emitted by the transmitting station.-

4. In a system of multiplex radio telephony, the combination with asource of electroradiant oscillations, of means for simultaneouslyimpressing'a plurality of series of undulations corresponding to soundwaves upon the said oscillations, and receiving means includingaplurality of devices selectively responsive respectively to saidplurality of series;

5. A transmission system for multiplex radio signaling, comprising atransmission circuit, a-plurality of secondary circuits connected tosaid transmission circuit, an electric arc, a source of electric energyconnected to said are for energizing the same, and a plurality ofoscillation circuits tuned to different frequencies respectively andrespectively coupled to said secondary circuitsfand shunted around saidare.

6. A transmission system for multiplex radio signaling, comprising atransmission circuit, a plurality of secondary circuits connected tosaid transmission circuit, an electric arc, a source of electric energyconnected to said are for energizing the same, a lurality of oscillationcircuits tuned to dili erent frequencies respectively and respectivelycoupled to said secondary circuits and shunted'around said arc, and a sialing-device arranged to act upon eac' of said secondary circuits.

7 A multiplex'system comprising a single are, a pluraht-y' ofoscillation circults tuned to different frequencies respectively andconnected to said arc, a single antenna operatively connected to saidcircuits and a Sig-- naling device arranged tocontrol each of saidoscillation circuits whereby a plurality of messages may besimultaneously transmitted through said antenna.

8. A multiplex system comprising a single are, a plurality ofoscillation circuits tuned to different frequencies respectively andconnected to said arc, a single conductor operatively connected to saidcircuits and a sig-' vices associated with said circuits respectivelywhereby a plurality of different messages may be simultaneouslgenerated.

10. In a system of multiplex signaling, an oscillator having an electronemittin cathode a plurality of circuits associate with said oscillatorand arranged to have simultaneously generated therein respectively, as

the result of the action of the oscillator, a plurality of series ofperiodic electrical impulses having diflerent frequencies respectively,and a plurality of signaling devlces associated with said circuitsrespectively whereby a plurality of different messages may besimultaneously generated.

11. In a multiplex system of signaling, the combination with anoscillator, of a plurality of circuits associated therewith and arrangedto have simultaneously produced therein respectively as a result of theaction of said oscillator, a plurality of series of periodic electricalimpulses having different frequencies respectively, one of saidfrequencies being substantially outside of the range of audibility, anda plurality of signaling devices associated with said circuits"respectively whereby a plurality of diiferent messages may besimultaneously generated, one of said signaling devices associated withthe circuit having-generated therein a frequency substantially outsideof the range of -audibility, being a telephone transmitter.

12. A multiplex transmission system com prising a thermionic oscillator,a pluralit of circuits associated with said oscillator and arranged tohave generated therein respectively as a result of the action of saidoscillator a plurality of series of periodic electrical impulses ofdifferent fre uencies respectively, and a plurality of signa ing devicesassociated with said circuits respectively whereby a plurality ofdifferent messages may be simultaneously transmitted.

f ranged to have generated therein respectively as a result of theaction of said oscillator, a plurality of substantially ultraaudibleperiodic electrical impulses of diiierent frequencies respectively, anda plurality of separately operated signaling devices as sociated withsaid circuits respectively whereby a plurality of different messages maybe simultaneously transmitted.

14:. In a system of multiplex radiotelephony, a sending stationcomprising telephone transmitting apparatus; va plurallty of0scillationcircuits connected with a single arc, sald osclllatloncircults generating a plurallty oi series of electric Waves of differentfrequencies respectively, each of said series of Waves having amplitudevariations impressed thereon by said telephone transmitting apparatus,and a receiving station compr sing a plurality of circuits tunedrespectively to said i requen'cies.

15. In a system of multiplex radio telephony, the combination with asource of electroradiant oscillations, of means for simul taneouslyimpressing a plurality of series of undulations corresponding to soundwaves upon the said oscillations, and receiving means including aplurality of devices selectively responsive respectively to saidplurality of series. a

This specification signed and witnessed this 22nd day of May A. 1).,1912.

JOHN HAYS HAMMOND, JR.

In the presence of- MABEL J. Coornn, OLIVE B. RING.

